Pro Tips For Buying a Backpacking Sleeping Bag

By Michael Lanza

Finding a sleeping bag that’s right for you may be the most confusing gear-buying task. Getting the right one is critical to sleeping comfortably in the backcountry—and in an emergency, your bag could save your life. But with the myriad choices out there, how do you tell them apart, beyond temperature rating and price? This article will explain how to evaluate the key differences between bags to make your choice much more simple.

I’ve slept in many, many bags of all types over more than a quarter-century of testing gear—including the 10 years I spent as the lead gear reviewer for Backpacker magazine and even longer running this blog. I’ve zipped inside bags in all seasons, in temperatures from ridiculously warm to -30° F. (Ridiculously warm is more tolerable.)

In this article, I’ll share what I’ve learned about picking out a sleeping bag—or more than one bag—that will be ideal for your body and your adventures.

I’d love to read what you think of my tips or any of your own. Please share them in the comments section at the bottom of this story. I try to respond to all comments. Click on any bag photo below to read its review.

Hi, I’m Michael Lanza, creator of The Big Outside. Click here to sign up for my FREE email newsletter. Join The Big Outside to get full access to all of my blog’s stories. Click here for my e-guides to classic backpacking trips. Click here to learn how I can help you plan your next trip.

Feathered Friends Hummingbird UL 30 sleeping bag.
The ultralight and warm Feathered Friends Hummingbird UL 30 sleeping bag, with 950+-fill down. Click photo to read the review.

General Tips For Buying a Sleeping Bag

•    Know your own body. Do you get cold easily or are you a furnace? Women tend to get cold more easily, and this is a simple function of physics: Women often have a higher ratio of body surface area to mass compared to men, so their bodies lose heat more readily. Those women are more comfortable in a bag made for women, which is shaped differently than a men’s bag and typically has extra insulation in areas like the feet. However, it also comes down to body metabolism.
•    If you get cold easily, get a bag rated 20 to 25 degrees colder than the coldest temperatures you plan to sleep outside in.
•    If you don’t get cold easily you may be more comfortable in a bag rated about five to 15 degrees below the coldest temperatures you plan to sleep outside in—and possibly even a bag rated right around the coldest temp you’ll encounter, provided you have extra clothing to put on, just in case. (I’ve spent many nights around freezing perfectly warm enough in a bag rated 30-32° F.) Being too hot is not really any more comfortable than being too cold and having a bag much warmer than needed means you’re carrying superfluous weight and bulk. (See “A Practical Guide to Lightweight and Ultralight Backpacking.”)

See “10 Pro Tips for Staying Warm in a Sleeping Bag.”

The Mountain Hardwear Phantom 30 sleeping bag.
The Mountain Hardwear Phantom 30 sleeping bag. Click photo to read my review.

Down Vs. Synthetic Bags

Down has traditionally been lighter, more packable, and warmer than many synthetic insulations; but once wet, synthetics still kept you fairly warm, while down feathers become all but useless at retaining heat. Today, the lines between down and synthetic have been blurred somewhat with the development of high-quality, lightweight and compact synthetic insulations like PrimaLoft, and water-resistant down, which retains its ability to trap heat even when wet. 

Down is more packable and very durable, so it still holds an advantage as the insulation of choice if you don’t expect to get that bag wet; and water-resistant down enhances your bag’s performance in common circumstances where it may get damp, such as when condensation builds up inside a tent. Still, even water-resistant down, once saturated, loses much of its ability to keep you warm, and drying out any bag is extremely difficult, if not impossible, in prolonged, wet weather. Synthetic insulation remains the best choice for extended trips in wet environments.

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Therm-a-Rest Hyperion 32F/0C sleeping bag.
The one-pound Therm-a-Rest Hyperion 32F/0C sleeping bag. Click photo to read my review.

High-quality down (rated from 800- to 900-fill or higher) is the warmest, lightest, most packable insulation out there, but expensive, while lower-quality down (usually 600- to 700-fill) still has the advantages of down and makes a bag less expensive but also heavier and bulkier. Manufacturers use lower-grade synthetic insulation in bags priced cheaply, making them much heavier and bulkier than better synthetic and down bags—typically too heavy and bulky for backpacking (unless you’re on a very limited budget and don’t mind carrying a big pack).

So the down vs. synthetic choice still comes down to pocketbook issues and the likelihood of your bag actually getting wet.

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A backpacker on the Tonto Trail above the Colorado River, Grand Canyon.
Mark Fenton on the Tonto Trail in the Grand Canyon. Click photo to see “America’s Top 10 Best Backpacking Trips.”

Temperature Rating

In the past, bag manufacturers decided on temperature ratings for their own bags; the outdoor industry lacked a standardized method for measuring that. In recent years, though, the industry widely adopted the EN (European Norm) temperature rating system, internationally considered the most reliable and objective standard.

Found on most new bags, the EN rating typically includes three temperature ratings:

•    Comfort rating, or the lowest temperature at which the bag will keep the average woman warm (based on the premise that women usually get cold more easily than men).
•    Lower-limit rating, or the lowest temperature at which the bag will keep the average man warm.
•    Extreme rating, or the lowest temperature at which the bag will keep someone alive, albeit not comfortable, in unexpected, extreme conditions.

Get the right tent for you. See “The 10 Best Backpacking Tents
and “5 Tips For Buying a Backpacking Tent.”

See all of my reviews of sleeping bags and air mattresses and sleeping pads that I like at The Big Outside.

See also my related stories:

5 Expert Tips For Buying the Right Backpacking Pack
10 Tips For Spending Less on Hiking and Backpacking Gear
5 Expert Tips For Buying a Backpacking Tent
A Practical Guide to Lightweight and Ultralight Backpacking
5 Smart Steps to Lighten Your Backpacking Gear

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America’s Top 10 Best Backpacking Trips

Thru-Hiking the John Muir Trail: What You Need to Know


Leave a Comment

29 thoughts on “Pro Tips For Buying a Backpacking Sleeping Bag”

  1. Hi, thanks for the article.
    Having no prior experience in sleeping bags, Im in a situation where I’m having to sleep in my car for upcoming 3-4 month. I bought cheepo Tesco mummy sleeping bag with hoody, and soon realised that it’s too cold and bought another rectangular one, and I put my mummy bag inside rectangular one essentially sleeping in two bags. Temps go as low as -5° and I feel relatively comfortable with layered clothes. It’s been two weeks now and one thing I’m struggling with is breathing. The air inside the car is getting too cold to breathe towards morning 3-6am. Would you possibly have a suggestion on this issue ? I’m currently covering the hoody all they way up to leave just a small gap to breathe, but this proves to be unstable. Thank you.

    • Hi Fred,

      I’m honestly not sure why the air is too cold to breathe. I’ve slept outside in air temps of -5 F and much colder without having any trouble breathing (including, most recently, this past December), as have countless other people. However, if your combo of two bags leaves gaps that allow too much cold air inside, it sounds like you just have an inadequate bag system for your circumstances. IF you can replace that with better bag(s), I’d suggest doing so. Combining two bags isn’t a bad idea, since temps will get warmer through spring and summer and you’ll only need one bag. Good luck.

  2. I’m looking for a bag to bike pack with as well as a sleeping pad.
    I toss and turn during the night and am also a side sleeper. Plan on getting a synthetic bag around zero to +20 rating. Im 6’1” and 270lbs so need a bag for big and tall.

    • Hey Stephen,

      For bikepacking, you probably want a lightweight and compact/packable bag. I’m not sure why you’d want to go as long as zero degrees for a bikepacking bag, unless you plan to take most trips at times when you’ll have nights far below freezing; and a zero bag will be heavier and bulkier. Look for a synthetic bag with higher-quality insulation, like PrimaLoft, which is more packable.

      Check out all of my reviews of sleeping bags and air mattresses.

      Good luck.

  3. Thank you for your reply! It’s a hard decision since I do not have much camping or backpacking experience. I was specifically looking at a the Mountain Hardwear Bishop Pass, but might still go with the 15-degree version since it only has 650 down fill and a better draft collar and might be good for shoulder seasons (when there are less crowds), but the 30-degree is certainly smaller and lighter…

    • Yup, Jason, you’ve point your finger on the tradeoff there: weight versus seasonal range. However, having a bag that’s too warm for your camping temps is not really any more comfortable than one that’s not warm enough. While you can wear an extra layer or two in a bag if it’s not warm enough, you can’t really make a bag that’s too warm comfortable because you need something covering you but that bag is too much.

      Good luck.

      • Sm I the only one that takes only a sheet with her camping in summer months?

        I mess as n I take my sleeping pad , and 1-2 satin sheets I use my clothes comp sack as a pillow and it keeps me toasty toasty and takes up less space than my towel. I may be doing something wrong during te day that keeps my tent soooooo hot still at night but I’m even able to sleep completely naked without rainfly fully on ( I peel the corner so I can see the stars) and I’m so hot still!
        Ok like 3 hours in the midsts of the night that sheet feeels incredibly cozy warm and I’m happy BUT I see 50 degrees sleeping bags going for 300+$ and I scratch my head am I the only one?

        Does anyone else?

        • Hi Hadi,

          I’m sure you’re not the only person who will forego a sleeping bag on warm summer nights and bring just a sheet or even a very lightweight liner bag or travel sheet. That works on quite mild nights for people who don’t get cold too easily. In mountains where overnight temps can drop into the 40s and even the 30s Fahrenheit in summer, that won’t work for everyone, particularly people who get cold more easily.

          But you’re right, that’s a good, functional sleep “system” for warm summer nights.

          Thanks for the comment.

  4. Hi, I enjoyed your article about sleeping bags. I’m buying my first down sleeping bag. Would you recommend a 15 or 30 degree F rated bag for 3-season camping mostly in California? I thought warmer better just in case and can always unzip but then have been told it may be better to get a 30 F bag and can use a liner for added warmth.

    Thank you so much for your advice,


    • Hey Jason,

      Thanks for the good question, I’m sure it’s one a lot of people wonder about. I remember thinking the same thing when I bought my first down bag: I’ll get the warmest bag I may need and open it up if needed. As it turned out, I usually opened it up because I didn’t need a 15-degree bag for summer and three-season camping and backpacking. So I had bought a bag that was often too warm, heavier and bulkier than a 30-degree bag, and probably cost me more.

      I backpack in the Sierra frequently—-I’m planning two backpacking trips for this month and hoping the fires don’t prevent them—-and I usually go in September, which is a bit cooler than mid-summer, and I always sleep warmly in a 30-degree bag. If needed for the unusually chilly night, I’ll wear a long-sleeve top and long underwear, socks and maybe a wool hat, but I usually don’t need that much in the highest California mountains even in September. That should give you some perspective.

      As I wrote in the above story, individuals differ in how easily they get cold and I fall somewhere on the not easily side of the spectrum. That said, I use a 30-degree for sleeping outside in most U.S. mountain ranges throughout the summer and in the desert Southwest in spring and fall—-basically until I expect nighttime lows near or below freezing.

      I hope that helps. Let us know what you get and how it works out for you.

  5. Hey Mike,

    I’m finding I come to your website more and more. Your putting out some incredible content. I really appreciate it!

    Question for you: how do Western Mountaineering bags compare to Feathered Friends? And do you have any good suggestions for a women’s bag? We live in Boise as well but do most of our hiking in the sawtooths, Tetons, and the Winds. I just can’t get enough of the Winds. So most of our experiences are at elevation, giving us a need for warmer bags.

    Let me know what you think.



    • Thanks, Scott.

      Western Mountaineering and Feathered Friends both make high-quality down bags that last a long time. I bought a WM bag in the early ’90s (before I was reviewing gear professionally) and it lasted 20 years before I finally sold it to someone who probably got at least a few more years out of it. And I’ve tested and reviewed good bags from both brands at this blog (link the above links).

      I find that I tend to feel more comfortable in the dimensions of Feathered Friends bags. I don’t like ultralight bags that are too confining and I’m pretty average size (5′ 8″, 155 lbs.).

      For a great, three-season women’s bag, I’d recommend the Feathered Friends Egret UL 20- or 30-degree. Very warm, light, and packable. (You can support my blog, at no cost to you, by buying that bag through the affiliate link in that review.)

      Thanks for asking and good luck.

      P.S. I also can’t get enough of the the Wind River Range. Hoping to get back there again next month.

  6. Hey Mike,

    What are your thoughts and experience with Western Mountaineering sleeping bags? I’m trying to decide whether it’s worth the extra $$ to go with either of these high end sleeping bags. Do you find it is worth it to pay that much more for a sleeping bag compared to a Sierra Designs or Nemo? .

    • Hi Scott,

      It’s a fair question to consider whenever you’re thinking about shelling out extra money for gear and apparel. In my experience, sometimes it’s worth the money and sometimes not—and that depends as much on the user as the gear item. If you’re not going to use a piece of gear and apparel in a way that justifies the purchase—if you’re not taking advantage of the features that drive the price higher—then there’s no point in spending that much.

      That said, I often advise friends and readers that if they’re able to spend more, they’ll often find it’s a good decision. With sleeping bags, as I point out in this story, differences aren’t always obvious. But with high-end brands like Western Mountaineering and Feathered Friends, look at the specs and you’ll find indicators of why the price is higher. The fill weight and quality (fill power rating) of they down in the bag are quite often both higher than found in other bags of the same temperature rating—meaning the bag is often both lighter and warmer. The quality of construction, the hood, and fit are often better.

      That’s not to argue that you’ll be disappointed with a less-expensive bag—and if that’s what you can afford, or you’re trying to figure out how to spread out your gear budget on multiple items, that’s a smart calculation and there are good bags out there at mid-range prices. But I’ve rarely been disappointed with high-end gear.

      Check out my stories “Why and When to Spend More on Hiking and Backpacking Gear” and “10 Tips for Spending Less on Hiking and Backpacking Gear,” the latter helpful even (and maybe especially) when you’re looking at expensive gear.

      I hope that’s helpful. Thanks for the comment and keep in touch.

  7. Good morning Michael. I hope you don’t mind all the questions, but you are the most knowledgeable person I’ve found on outdoor gear and I want the best source I have for answering these questions. I’m reading through all of your sleeping bag reviews and I’m confused on which one I want.

    I’m 5 foot 11 and weigh 160 lbs. and I get cold easily. The places I will be backpacking over the next few years are the Ozarks, Smokies, and Southern Appalachian mountains mainly in spring and fall. The temps are mild here compared to western mountain ranges but still can get pretty cold at night during those times of the year.

    I’m also trying to be as Ultralight as possible with my gear. I’m confused on which sleeping bag can handle 30 degree nights on low end but also not make me burn up if the temps are in the 70’s at night because as you know in the south the weather can swing either way dramatically from day to day. Any thoughts on a bag that might be perfect for me for these conditions?

    Thanks again so much!


    • Hi Slade,

      Yes, it can be hard to sort through all the sleeping bag choices out there. The above article should help you narrow your preferences, but I’ll offer some suggestions.

      I’d go for a 30-degree bag because a warmer bag will feel like too much on those nights in the 40s, 50s, and warmer. But if you get cold easily AND frequently backpack on nights in the 40s and 30s—and that question should be a primary driver of your decision—then get a 20-degree bag.

      For maximum warmth per ounce of bag, high-quality down—800-fill or higher—is unquestionably the way to go. It costs more but I always consider the cost per night or mile of use I’ll put on gear. Plus, the high-end bags are often stuffed with more insulation and built better than less-expensive models. You’ll probably get your money’s worth out of a good bag.

      My top recommendation for you is the Feathered Friends Hummingbird 30 or 20. Another good one, though not quite as warm (though similarly rated), is the Therm-a-Rest Hyperion 32. For a 20-degree down bag, the Sierra Designs Nitro 800 is a good one.

      You can support my work on my blog by purchasing through any of the affiliate links to online retailers in those reviews.

      Good luck.

      • Thanks Michael! I really appreciate you taking the time to answer my questions. You have helped me more already than I ever imagined when subscribing to The Big Outside. I’m very grateful.

  8. Hi Michael,
    I am like you in that I don’t get cold easily. For summer backpacking trips I have generally used a 30 degree bag, such as a Marmot bag. I also have a Mountain Hardware Phantom 32, but it does not seem as warm; and also I prefer a full length zipper. In general I bring a 30 degree bag and also may bring a bag liner if I might need extra warmth (such as a mid to late September trip in the Canadian Rockies). I am curious what specific sleeping bag you use in your summer hiking trips, e.g., a hike in the Sierras in August or early September?

    • Hi Jeff,

      Thanks for asking. I don’t get cold too easily, but I also find that I can wear a couple of base layers, long underwear, socks and a hat in my bag to supplement its warmth when needed (and I’m often wearing the socks and hat, even if just in a T-shirt and underwear). You might find my “10 Pro Tips for Staying Warm in a Sleeping Bag” useful.

      I’m often testing a new bag on my trips (to review), but like you, I generally take an ultralight, 30-degree, down bag on summer trips in mountain ranges like the High Sierra and throughout the West, including the Canadian Rockies (where I have plans to backpack this summer, crisis-permitting). I have used Hardwear’s Phantom and found it adequately warm for September in the Sierra, and various Marmot bags, which are usually plenty warm.

      Some bags I’ve liked and reviewed recently include the Therm-a-Rest Hyperion 32, the REI Magma series, and the more-affordable, synthetic Nemo Kyan/Azura series.

      I hope that’s helpful. I’ll certainly be testing and reviewing more bags this summer. Thanks for the comment.

      • Yes I do very much the same – I wear a couple of wool base layers, long underwear, socks and a toque hat in my bag to supplement its warmth. This has the added benefit of when I get up in the middle f the night to “use the facilities” it is not such a huge temperature shock. I also bing a silk bag liner.

        I am looking at the Feathered Friends Flicker UL Wide sleeping bag / quilt, which looks very interesting to me.I am not sure how I will fare without a sleeping bag hood, but often times I wear my down jacket to bed, and for my head I can wear a buff, a toque (warm beanie) over the buff and can also put on my warm jacket hood as well. The other option is the Feathered Friends Swift UL 30 degree bag, which is more of a traditional sleeping bag. If you have any wisdom to share on these I would love to hear it.

        Thanks for the answer!

        • Hey Jeff,

          I haven’t used either of the Feathered Friends bags you mentioned, but I am a fan of Feathered Friends products in general. (See this menu of my FF reviews.) They make great bags that tend to be among the warmest bags in any temperature rating category.

          I have not embraced quilts because I shift in my sleep. I generally like a bag with a hood, though a hat often suffices in the temps in which I’d use a 30-degree bag; if I’m pushing that bag’s temp rating, though, I’d like to have the hood.

          I hope that’s helpful.

  9. Hi Michael,

    Have you tried any of the ultralight quilts from smaller companies (Katabatic Gear, Nunatak, etc.)? They seem like a great alternative to three-season bags, especially for side and stomach sleepers who don’t usually use a hood. It’s a bit difficult to find reviews of them though, as they aren’t as widely used as mummy bags. I was just wondering if you’ve had any positive or negative experiences with them


  10. I think a full-length zipper is most-useful in the summer. It lets you open the bag fully and use it as a quilt instead. You’re right that being too warm is uncomfortable, and it makes you sweat. That moisture is bad no matter what kind of insulation you use.

    That seems to be the problem with getting wet. I’m knocking on wood as I type this, but I’ve never completely soaked my gear while fording a creek or capsizing a boat. It’s condensation and possibly sweat that are going to wet your bag, I think.

    I’m starting to experiment with carrying a lighter and less warm bag than most people would suggest, and making up the difference by sleeping in a down hoodie jacket and down booties. (Feathered Friends makes down socks with a removable boot shell.) You only use the bag when you’re sleeping, but the jacket and boots are useful in camp (stargazing for example) and sometimes when you stop on the trail. So I feel like this is probably a good way to split up the weight. But I need more trips to test this idea.

    • Good points, Forrest. I agree about the full-length zipper being most useful in mild temperatures. I’ve rarely gotten my sleeping bag very wet, partly because I will use a waterproof dry bag-style stuff sack whenever I’m on a water-based trip or backpacking in a situation where I could get very wet. I like the Sea to Summit eVent Compression Dry Sacks for that:

      But in general, the more common reason a bag gets wet is from condensation, either on the interior tent walls or directly on your bag (from body heat), which occurs in colder temps, i.e., just above or below freezing. If it’s below freezing, you can conveniently knock the frost or ice off your bag first thing in the morning. If the condensation isn’t frozen, you can wipe surface dampness off the bag’s shell. But on prolonged, below-freezing trips, condensation can collect inside the bag’s insulation, so it becomes important to dry the bag in warm sunshine whenever possible. A synthetic bag is obviously better if the insulation gets damp, but they’re very bulky. The new types of water-resistant down bags are a good choice for long, cold trips.

      I also prefer to take as light a bag as I know I can get away with using on a trip, given the anticipated coldest temps, and using my extra clothes for added warmth as needed.

      • I appreciate and thank you for your sleeping bag temperature guide lines. Have you made comments regarding hood/no hood, size (particularly width), zipper location, size, length, and jamb protection, fabric material, pad and liner attachments?

        • Good questions, Arthur. Some of those, like zipper location, mostly come down to personal preferences. Most bags come with a hood and I consider it essential in any temps below the low 40s Fahrenheit (although some dedicated quilt users may disagree); again, that depends on how easily you get cold. Sizing information is generally available from the brand or manufacturer, website, or a store salesperson. A draft tube inside the zipper is an important feature, and again, almost universally provided in backpacking bags, with its size proportional to the bag’s temp rating. As for factors external to the bag, you may want to check out my “10 Pro Tips for Staying Warm in a Sleeping Bag.”

          Thanks for the questions and keep in touch.